In known displays of this kind the ends of the beams are provided with male bayonet fittings which are inserted into the female node fittings. The bayonet part of the fitting is substantially T-shaped. The cross-piece of the T is inserted through an elongate aperture in the female part and rotated through 90° into a detent position to releasably lock the beam to the node fitting. Whilst such connectors have been used successfully for many years the existing system has been found to possess a number of shortcomings.
1. During construction of the display considerable attention must be paid to the orientation of the node fittings and beams to ensure that they all interconnect in the desired manner. This takes up a considerable amount of time and pre-planning, and requires skill and experience on the part of the display erectors.
2. In order to ensure that a tight rigid joint is achieved the connectors must be designed such that a significant amount of force is necessary to rotate the bayonet fitting. Furthermore, if the connectors should become worn or damaged following a prolonged period of use the connection could become slack, reducing the overall stability of the display frame.
3. It is not immediately obvious whether the beams are securely attached to the node fittings since the external appearance is very similar whether the beams are rotated into the locking position or not.
4. The requirement to rotate the beams through a relatively large angle is sometimes difficult when access is restricted.
5. The weight of the display is attaining greater significance with the need to reduce transportation costs and ensure greater public safety. Although the existing system uses aluminium extruded beams it is necessary to fix steel tape on at least two sides of the beam to which the display panels can be magnetically attached.
U.S. Pat. No. 4,646,503 discloses a display connector in which the male bayonet fitting has a cruciform (cross-shaped) head which is rotatably inserted into a square aperture in the female node fittings. The joint is tightened by means of locking wedges which are operated by means of jackscrews. Although this requires a smaller angle of rotation with a minimum amount of force a secure joint is only achieved if the jack screws are adequately tightened, and there is no visual indication that this has been done. Furthermore, a large number of components are required, making the system expensive and unreliable.
The present invention seeks to provide a new and inventive form of connector for use in the construction of such displays which avoids the above disadvantages, reducing the need for consideration and pre-planning of the build, reducing the overall construction time, minimising the weight, and generally increasing the ease of construction.